The present invention relates to electromagnetic devices for determining angular position, for example, the angular position of a rotary shaft or joystick or of an incoming electromagnetic wave at a receiver.
A number of conventional devices for determining angular position incorporate AC synchros. However, these have the disadvantage that their construction is relatively complex, requiring a rotating electromagnetic coil and sliding contacts. Consequently, such devices tend to be unreliable and, due to the fact that the moving and stationary parts are mechanically coupled, are not suited to application where robustness and low frictional torque are desirable, for example, in determining incident wind direction on board ship.
Other known devices for determining the angular position of a rotating body use optical or capacitive sensing techniques. However, such devices are adversely affected by environments with a high moisture content such as are found on board ship and, as they cannot be adequately sealed against the entry of moisture due to the low torque requirement, are not, therefore, suited to marine applications.
These difficulties have been overcome, to a certain extent, by using potentiometric sensing devices. However, such devices can only be made using specialist techniques and their manufacture frequently requires heavy investment in specialized plant.